I agree with dsc. I've found that reef crystals is high in Ca and I have to add alk to compensate. I also use 4 gal reef crystals to 1 gal instant ocean. This results in Ca around 400-425 and alk around 10. I dose 2 ml Ca and 8 ml alk twice a day (40 gal tank). The perams have been right on the money and there is almost no bump when I change water (5 gal/week). I also add 4 ml Mg to change water. I'm using BRS 2 part system.

Thank you for reply and support all much appreciated,
I want to try and keep my existing salt and get it to target by dosing,
I do have some baking soda and calcium flakes, how should I dose these
With the Kent tech cb I have been dosing 2tsps calcium and 2 tsps alk straight after, could this be a problem and should I wait longer in between dosing each,

Others on this forum have much grater experience with this issue but I'll make my suggestions. Ca is much more stable and chews through carbonate. I would suggest either reducing Ca or increasing carbonate systematically. Pick your method and measure the same time of day. Really, you are close to having it under control. What I would do is cut the Ca in half and see what happens over the next day. Also, I've found that salifert is a reliable kit for the big three. I've used API and red sea for Mg. API was clearly off. Not sure about red sea.

Yeah, Don't dose both at the same time. As long as it is staggered for enough time to circulate through out the system it should be ok but best to do one in AM and one PM.
Surprised the mag didn't help though. Sure sounded like the classic low mag scenario.

That's what makes aquavitro awesome. You can dose calcium, mag and alk within minutes of eachother. I've used it for years. Switching your salt will handle most of your issues and possibly save you money in the long run. Reef crystals isn't much more than the regular IO.

ok, i dosed 2 tsps of alk this morning before lights on, this raised it to 6dkh, will leave it 12 hours before adding the calcium part, see if i get any other result this way over the next couple of days,
im nearly out of kent tech cb so then i will use the baking soda and calcium flake

changing salt at the moment i really dont want to, i just bought a brand new 25kg of io reef, its not cheap and i wont get back what i paid

The next 4 days i will test water before lights come on then i will dose alk, 12 hours later i will dose calcium and test both before bed and before lights come on.

Until your Magnesium is stable, don't even try to adjust anything else. I know you list it as 1320 and that should be alright, but as someone else here has said, your problems sure sound exactly like the problems someone with a too low magnesium level would have. I know - I'm an expert. I had these problems and didn't understand why.

I'm going to suggest you find a way to eliminate the magnesium variable issue. Get another test kit or find a way to have someone reliable crosscheck your result. Then get your reading up to 1400 or 1450 (thats a bit high, but still safe and much easier to live with than having it too low).

When your mag is right, and only then, start trying to adjust your calcium and alk.

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